Distributed Coupling Structure for EMI Suppression
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Solution Overview
Problem
Conventional electromagnetic noise suppression methods are ineffective for high-frequency digital circuits and require costly multi-layered structures, limiting their applicability to low frequencies, while existing solutions are not easily fabricable or cost-effective for wide frequency bands.
Innovation Solution
An electromagnetic noise suppression circuit utilizing a distributed coupling structure with bended transmission lines and metal pads configured on substrates, forming coupling capacitors and equivalent inductor-capacitor resonant circuits to suppress noise across a broader frequency range, with options for coplanar or non-coplanar connections to a grounding plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electromagnetic materials with high inductance are adopted to eliminate EMI at low frequencies, then EMI suppression is achieved, but the method is not applicable to high-frequency digital circuits and requires large hardware instrumentality
Solution Approach 1:
The grounding plane is segmented into multiple distributed coupling structures instead of using a conventional continuous high-inductance material. This segmentation allows the structure to function across different frequency ranges by creating multiple coupling points that interact with the transmission line at different frequencies, thereby achieving both EMI suppression and broad frequency applicability
Solution Approach 2:
The invention transitions from using bulk electromagnetic materials (three-dimensional approach) to a planar distributed coupling structure (two-dimensional approach) integrated into the PCB layer. This dimensional change reduces hardware instrumentality while maintaining EMI suppression effectiveness across wide frequency bands including high-frequency digital circuits
2Reliability
If multi-layered electromagnetic noise suppression circuit using LTCC/HTCC technology is adopted, then EMI is effectively suppressed, but the technology is very costly and only capable of operating at low frequencies
Solution Approach 1:
The distributed coupling structure serves multiple functions: it provides EMI suppression, acts as a grounding mechanism, and enables broad frequency operation (from low to high frequencies including digital circuits). This multi-functionality eliminates the need for costly specialized multi-layered LTCC/HTCC structures while achieving superior frequency coverage and cost-effectiveness
Solution Approach 2:
Instead of using expensive multi-layered ceramic structures, the invention creates a planar copy of the noise suppression function using standard PCB fabrication techniques with distributed coupling elements. This approach achieves the same EMI suppression effect at a fraction of the cost and with much broader frequency applicability
3Ease of manufacture
If a simple grounding structure is used, then fabrication is simple, but electromagnetic noise within wide frequency bands cannot be suppressed
Solution Approach 1:
The grounding plane is divided into multiple distributed coupling structures with different geometries and positions. This segmentation creates multiple resonant frequencies and coupling effects that collectively suppress EMI across a wide frequency spectrum, while still using simple planar fabrication techniques compatible with standard PCB processes
Solution Approach 2:
Different regions of the grounding plane are assigned different coupling structures with varying sizes, shapes, and positions optimized for specific frequency ranges. This local differentiation enables broad frequency coverage while maintaining overall fabrication simplicity through standard PCB layer integration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses electromagnetic noise within a designated frequency band, reducing interference with signal transmission and electromagnetic radiation, while being more cost-effective and easily fabricable compared to existing technologies.
Implementation Method 1
at least one coupling capacitor is formed between the transmission line and the first metal pad
Implementation Method 2
the transmission line and the distributed coupling structures are configured to be equivalent to an inductor-capacitor resonant circuit for suppressing electromagnetic noise within a plurality of designated frequency bands
Data Source
AI summary
An electromagnetic noise suppression circuit is provided. The suppression circuit comprises a first substrate, a first grounding plane and at least one transmission line. The transmission line is configured on a top surface of the first substrate and the first grounding plane is configured on the bottom surface of the first substrate. The first grounding plane comprises a first distributed coupling structure. The first distributed coupling structure and the transmission line can be equivalent to an inductor-capacitor resonant circuit. The electromagnetic noise within a designated frequency band can be suppressed by the distributed coupling structure of the electromagnetic noise suppression circuit to avoid interfering the signal transmitted by the transmission line and the electromagnetic radiation induced by the electromagnetic noise.